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121 Chapter V Discussion workers in the field (Havenaar et al., 1992; McCracken and Gaskins, 1999; Bezkorovainy, 2001; Dunne et al., 2001), as well as a Joint FAO/WHO working group (Chesson et al., 2002), in vitro studies can only partially mimic the actual in situ conditions in the gut ecosystem. Nevertheless, such in vitro systems are powerful tools especially for screening numerous samples. Six new potentially probiotic isolates were selected on the basis of their good survival properties under in vitro simulated stomach-duodenum passage. Further phenotypic and genotypic characterization of six strains revealed two strains as L. casei (LAM-1 and LAM- 2), the other two as L. delbruckeii (LKH-2 annd LKH-3), one as L. helveticus (LKH-3) and one as L. fermentum (Lamec-29). These strains were further investigated for their functional and probiotic attributes. Two L. casei strains (LAM-1 and LAM-2) stemmed from mango pickle, indicating the safe origin of the strains and also the ability of these strains to survive the passage through the harsh conditions in the gastrointestinal tract. The other selected strains (two L. delbruckei and one L helvictus) were isolated from traditional beverages Kharoli and Bhaati jaanr, respectively. A previous study conducted with several Asian fermented foods such as ‘‘suan cai’’, ‘‘kimchi’’, ‘‘natto’’ ‘‘mizo’’, ‘‘Nham’’ and ‘‘Miang’’ reported bioactive properties as well as the occurrence of LAB with interesting probiotic characteristics (Ramadan et al., 2005). However, pickled vegetables/fruits as well as beverages widely consumed in the Indian subcontinent especially as adjunct to main meals, have been rarely investigated for probiotic strains of LAB. Mahula liquor is prepared by the fermentation of flowers of Madhuca latifolia, claimed to have extensive medicinal properties, whereas Bhaati jaanr is made by fermenting rice. Both are extensively consumed in several rural areas of North Eastern, Eastern and Northern India.
122 Chapter V Discussion Lactobacillus is a normal inhabitant of the gut ecosystem (Tannock, 1999), and therefore it is not surprising, that they possess the capability to sustain conditions of gut. The strain L. casei, which was originally isolated from the fermented milk, is a known probiotic strain that is commercialized in country including india. This could also be an interesting alternative for developing a probiotic product without milk constituents using the L. casei strains characterized in this study. However, the two selected L. delbruckeii strains isolated from Kharoli, were present in low numbers in this product and were not representatively important as predominant species in the microbiota of this traditional fermented food. L. casei LAM-1 survived under low pH conditions for five hours and well tolerated bile acids under in vitro conditions even at concentrations higher than those previously used by other authors (Jacobsen et al., 1999; Fernández et al., 2003). Acid tolerance of bacteria is an important factor to assure their resistance of gastric stresses and also for their use as dietary adjuncts in acid foods such as yoghurt. Resistance to bile salts is considered as an important property for strains to be used as probiotics, however, there is still no consensus about the precise concentration to which the selected strain should be tolerant. The physiological concentration of bile acids in the small intestine varies from 5 to 20 mM/l (Hofmann, 1991). Therefore, a concentration of 0.5% ox- gall, equivalent to 12.25 mmol/l bile acids was used in this study, as was also previously done by Kociubinsky et al. (1999). This concentration is higher than the ones (0.3% and 0.15%) previously used by other investigators for judging bacterial probiotic properties (Chou and Weimer, 1999; Zarate et al., 2000; Fernandez et al., 2003). Another test for resistance to intestinal conditions used in this study was resistance to 0.4% phenol. Phenols may be formed in the intestine as a result of the bacterial deamination of some aromatic amino acids derived from dietary and endogenous proteins. These
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Characterization of Lactobacilli is
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their encouragement, insightful com
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5. Mukesh Kumar and Abhijit Ganguli
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2.3.2.9 Cholesterol lowering 2.3.2.
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Chapter 1 INTRODUCTION
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Rogosa agar Ingredients Quantity (g
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Denaturing solution. guanidinium is
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